Many fluid spraying devices, such as airless paint spray guns, are often fitted with extensions or wands to increase the reach of the operator. These extensions vary in length and consist primarily of a rigid tube able to withstand hydraulic pressures in a range of 2,000-3,500 psi. Wands are generally of short length, about 6 inches to 24 inches, and consist of a small tube section with a fitting at one end which attaches to a spray gun and a threaded section at the other end to accept the spray tip. An extension is generally of a longer length and encloses a small diameter, high pressure tube, or fluid section, within a larger tube section.
Spray tips are designed to provide a spray fan of an exact shape and size in order to evenly coat a surface. The directional relationship of the spray tip to the work surface is critical to the process of achieving even coverage. When the spray tip is remotely positioned at the end of a wand or an extension, the ability of the operator to angle or maneuver the spray tip becomes severely restricted. To maintain the relationship of the spray fan to the work surface when using an extension device, some sort of swivel or pivot mechanism must be fitted between the extension pole and the spray tip.
Most swivel devices that are presently in use, are constructed as separate units that are then attached to the extension pole. They do not constitute any part of the pole structure and the swivel action is generally 180 degrees of pivot or less. They are generally constructed using two overlapping assemblies with a bolt through the pivot access. One of the overlapping assemblies is threaded onto the pole, and the other is fitted with a threaded portion which accepts the spray tip. Both assemblies have hollow passages for the material flow. The key component is the bolt which forms the pivot access. The bolt is either of a hollow design or is solid and sealed at either end and then tightened to create a sealed area machined about it. These techniques allow fluid to flow from one pivoting component to the other without leaking.
The swivel devices described above are required to operate under high pressure, 2,000-3,500 psi, over thousands of pivot cycles without leaking, while still providing a low friction, easy to pivot, joint. To provide for both an effective pressure seal and bearing, washers or "O" rings of special design are fitted around the joint. Because these washers or "O" rings are required to fulfill the dual role as both a bearing and a seal, the washers have a built-in level of friction and offer no provision for being locked in place. Thus, the bearing washers are prone to wear in the abrasive environment in which they operate. As the wear increases on the bearing washers, leaks become a common problem.
For obvious reasons, leaks are a liability. High pressure fluid leaks can be a physical danger to both the operator and to those in close proximity. The current swivel devices must be built in a substantial manner and to exact specifications in order to withstand the pressures involved. Rigorous assembly standards must be maintained. Generally, they are a complicated and exacting component to manufacture and, regardless of the manufacturing care taken, they represent a certain level of liability risk. Additionally, the present swivel devices are constructed in such a way as to require the operator to physically grab hold of the spray tip itself to induce the force required for the swivel to pivot. Although the spray tips are fitted with guards of varying levels of protection, there is a risk of high pressure fluid injection to the hands or the fingers.
U.S. Pat. No. 5,546,749 shows an articulated nail gun handle extension. The abstract of the patent indicates that the tool is suitable for any air powered hand tool. The air supply line is tapped into the extension element and the device includes a jointed, tubular extension that affixed to the tool. It also includes a trigger mechanism that controls the operation of the tool, and a grip to allow the user to easily support the weight of the tool. U.S. Pat. No. 5,372,389, to Tam et al., reveals a prior art fitting which carries pressurized material, such as paint. The fitting is jointed and is the type of device in which the present invention is intended to replace.
It is the object of the present invention to provide an improved extension pole for use in airless fluid spraying, the extension pole being lighter, easier to manufacture and maintain, non-leaking, and having a swivel hinge assembly that can be easily adjusted and adaptable for use by the operator.